From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757754Ab3CZRzA (ORCPT ); Tue, 26 Mar 2013 13:55:00 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:23274 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753897Ab3CZRgP (ORCPT ); Tue, 26 Mar 2013 13:36:15 -0400 X-Authority-Analysis: v=2.0 cv=UN5f7Vjy c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=RukVFyfidrwA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=Tn2-2cLip6UA:10 a=1XWaLZrsAAAA:8 a=J1Y8HTJGAAAA:8 a=GZK3lcuhIWR5GrNAc6YA:9 a=UTB_XpHje0EA:10 a=4N9Db7Z2_RYA:10 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.67.115.198 Message-Id: <20130326173605.049879635@goodmis.org> User-Agent: quilt/0.60-1 Date: Tue, 26 Mar 2013 13:21:31 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Eric Dumazet , Neal Cardwell , "David S. Miller" Subject: [PATCH 32/86] tcp: fix for zero packets_in_flight was too broad References: <20130326172059.136127374@goodmis.org> Content-Disposition: inline; filename=0032-tcp-fix-for-zero-packets_in_flight-was-too-broad.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6.11.1 stable review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= [ Upstream commit 6731d2095bd4aef18027c72ef845ab1087c3ba63 ] There are transients during normal FRTO procedure during which the packets_in_flight can go to zero between write_queue state updates and firing the resulting segments out. As FRTO processing occurs during that window the check must be more precise to not match "spuriously" :-). More specificly, e.g., when packets_in_flight is zero but FLAG_DATA_ACKED is true the problematic branch that set cwnd into zero would not be taken and new segments might be sent out later. Signed-off-by: Ilpo Järvinen Tested-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 97cbfa9..8d02e34 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3511,8 +3511,7 @@ static bool tcp_process_frto(struct sock *sk, int flag) ((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED))) tp->undo_marker = 0; - if (!before(tp->snd_una, tp->frto_highmark) || - !tcp_packets_in_flight(tp)) { + if (!before(tp->snd_una, tp->frto_highmark)) { tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag); return true; } @@ -3532,6 +3531,11 @@ static bool tcp_process_frto(struct sock *sk, int flag) } } else { if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) { + if (!tcp_packets_in_flight(tp)) { + tcp_enter_frto_loss(sk, 2, flag); + return true; + } + /* Prevent sending of new data. */ tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)); -- 1.7.10.4